In the literature the occurrence of thymomas in goats varies from 0.7 to 25%, depending on the study. Therefore the current investigation was carried out to determine the prevalence of thymoma in goats in Poland. Between 2007 and 2018 at the Warsaw Veterinary Faculty 399 goat autopsies and ultrasound examinations of the chest in other 145 goats were performed. Mediastinal tumors were diagnosed during post mortem examination in 2 goats. Additionally, ultrasound examination of the chest revealed a large mass close to the heart in the thoracic cavity in 1 case. This goat was euthanized and an autopsy confirmed a mediastinal tumor. Histopathological examination, with immunohistochemical tests to anti cytokeratin, p63 and p40 confirmed thymomas in all three cases. In our study thymomas were found in 0.5% (95% CI: 0.1% to 1.8%) of examined goats and they represented the most common malignancy in this species.